The study, looking at the effect of chondroitin taken over two three-month periods during one year, supported the long-term results of the supplement for osteoarthritis, said an international team writing in the April issue of Osteoarthritis and Cartilage (vol.12: 269-276).
Osteoarthritis is a major cause of disability and there is neither an effective treatment to stop the disease worsening, nor a cure. The only available treatment is pain relief and replacing the worn out joints.
Knee osteoarthritis affects 14.1 per cent of men and 22.8 per cent of womenover the age of 45 but increases in life expectancy and ageing populations are expected to make osteoarthritis the fourth leading cause of disability by 2020, according to the World Health Organisation.
In the new study, the group taking chondroitin sulphate (800 mg daily) saw symptoms measured by Lequesne's algo-functional index (pain and knee function) decrease by 36 per cent after one year compared to 23 per cent in the placebo group.
Secondary measures of efficacy, such as walking time and paracetamol, also showed similar results.
And X-rays at the end of the study revealed that while the placebo group patients had significantly decreased femoro-tibial joint space width, there was no change in the chondroitin group.
The researchers conclude that the intermittent administration of chondroitin sulphate supplements twice a year supports the prolonged effect seen with other symptom-modifying agents for osteoarthritis.
They add that the inhibitory effect on progression of joint space narrowing could suggest further evidence of its ability to improve the condition.